Generic tensioners or tensioning devices are used for example for tensioning drive belts and control belts in motor vehicles and are intended to ensure, by ensuring an optimum traction mechanism tensioning force even as the traction mechanism ages, at all times optimum functioning and transmission of this force without slippage and without disruptive vibrations. In addition, the connection between the helical spring and axially end-side spring receptacles of the tensioner is intended to be non-detachable during transportation of said tensioner and to be sufficiently secure in dynamic mode. The helical spring can in this case be embodied as a traction spring or else as a compression spring. Embodiment as a compression spring can in particular give rise to the problem that a tear in the traction mechanism causes the compression spring suddenly to expand during operation and the tensioner to break up with high pressure (so-called snapping). This can lead to destruction of the traction mechanism drive as a whole. Generic tensioners are therefore equipped with a suitable means (snapping securing means) to delimit the spring excursion.
DE 195 01 685 C1 discloses a generic tensioner of this type in which the spring excursion delimiting means used is a sheet metal strip which is made of spring steel, is inserted coaxially into the compression spring, is held in a lower spring receptacle by a first securing pin and mounted in the opposing spring receptacle so as to be longitudinally displaceable via balls in a through-guide. In the region of the through-guide, the sheet metal strip is bent over at its end 90° about its longitudinal axis and axially held by a second pin, so that said second pin cannot, with the bent part, pass through the through-guide and said through-guide can thus serve as a spring excursion delimiting means for transport and also snapping securing. This tensioner is mounted on the traction mechanism drive with the spring tensioned and its belt pulley placed against the belt. For tensioning the belt, the securing pin is removed at the belt pulley-side end of the sheet metal strip, so that the compression spring expands as a tensioning lever pivots and presses the tensioning roller against the belt. During this tensioning process the sheet metal strip is displaced in its mounting. However, this does not normally lead to abutment of the stop, formed by the angled segment, of the sheet metal strip against the spring receptacle. This extreme stop state occurs only when the belt to be tensioned tears or stretches excessively owing to ageing or as a result of temperature influences. The described construction provides on this tensioner transport and snapping securing.